Diffusing gas turbine engine recuperator

Abstract

A method of diffusing and cooling an exhaust flow in an exhaust duct of a gas turbine engine includes circulating the exhaust flow from a turbine section of the gas turbine engine to a recuperator extending within the exhaust duct, circulating air discharged from a compressor section to a combustor of the gas turbine engine through air passages of the recuperator, and cooling and diffusing the exhaust flow by circulating the exhaust flow through exhaust passages of the recuperator having a progressively increasing cross-sectional area and in heat exchange relationship with the air passages.

1 . A method of diffusing and cooling an exhaust flow in an exhaust duct of a gas turbine engine, comprising:
 circulating the exhaust flow from a turbine section of the gas turbine engine to a recuperator extending within the exhaust duct;   circulating air discharged from a compressor section to a combustor of the gas turbine engine through air passages of the recuperator; and   cooling and diffusing the exhaust flow by circulating the exhaust flow through exhaust passages of the recuperator having a progressively increasing cross-sectional area and in heat exchange relationship with the air passages.   
     
     
         2 . The method as defined in  claim 1 , wherein circulating the exhaust flow from the turbine section to the recuperator includes circulating the exhaust flow through passages having a progressively increasing cross-sectional area and defined by circumferential splitters of a diffuser located in the exhaust duct. 
     
     
         3 . The method as defined in  claim 2 , wherein the exhaust flow circulates through the passages defined by the circumferential splitters along a path oriented progressively from an axial or substantially axial direction to a radial or substantially radial direction. 
     
     
         4 . The method as defined in  claim 1 , wherein circulating the exhaust flow through the exhaust passages of the recuperator further includes reducing a swirl the exhaust flow through the exhaust passages having an arcuate profile in a plane perpendicular to a central axis of the recuperator. 
     
     
         5 . The method as defined in  claim 1 , further comprising delivering the exhaust flow from the exhaust passages to atmosphere. 
     
     
         6 . The method as defined in  claim 1 , wherein the progressively increasing cross-sectional area of the exhaust passages is defined at least in a curved portion of the exhaust passages. 
     
     
         7 . The method as defined in  claim 1 , wherein cooling the exhaust flow includes circulating the exhaust flow through the exhaust passages and circulating the air through the air passages in a mixed counter flow and double pass cross flow configuration. 
     
     
         8 . The method as defined in  claim 1 , wherein circulating the air discharged from the compressor section includes circulating the air through a plenum in fluid flow communication with a discharge of a compressor of the compressor section and from the first plenum to the air passages. 
     
     
         9 . The method as defined in  claim 1 , wherein circulating the air to the combustor includes circulating the air from the air passages to a plenum containing the combustor. 
     
     
         10 . The method as defined in  claim 8 , wherein the plenum is a first plenum, and circulating the air to the combustor includes circulating the air from the air passages to a second plenum containing the combustor.